It is desirable, in order to reduce on site installation and maintenance time to be able to provide an industrial luminaire which may be quickly installed and maintained at the job site without having to use any special tools or open the luminaire to make wiring splices or connections. It is also desirable to provide an industrial luminaire in which the optical assembly can be easily removed and another optical assembly installed to provide different lighting patterns and distributions to accommodate different lighting needs or requirements. In addition it is desirable to provide an industrial luminaire which has an optical assembly which is easy to relamp, is totally sealed to exclude insects, dust and dirt, and is provided with adequate circulation of clean air through its heating and cooling cycles. Still another desirable feature of an optical assembly, is to provide means whereby the glass prismatic reflector is put under compression making it stronger and less likely to break when accidentally struck.
Previously, known luminaires would often be shipped to the contractor at a job site whereupon they would be opened by the electrician to expose the internal wires which would then have to be spliced to matching electrical wires in a previously installed outlet box, and if after installation a change in the lighting pattern and distribution was desired, it was necessary to change the entire luminaire. Similarly, special tools were often necessary not only to install the luminaire but even to replace the lamp. In addition adequate measures were often not provided to keep out insects, dust and dirt from within the optical assembly of the luminaire.